The present invention pertains to what is commonly known as “printer cartridges”. These cartridges may better be termed “imaging media cartridges” since they are configured to contain an imaging media, such as an ink or a toner. In order to facilitate handling of the imaging media by a user of the imaging apparatus, the imaging media is commonly provided within a container (a “cartridge”) that is configured to be installed in, and removed from, the imaging apparatus. The cartridge is typically designed to prevent leakage of the imaging media from the cartridge when the cartridge is handled by a user or installed in the device, but is also designed to allow the imaging apparatus to selectively remove the imaging media from the cartridge during an imaging process.
By “imaging apparatus” we mean any apparatus configured to use imaging media to generate an image on sheet media, such as on paper or a transparency. Examples of imaging apparatus include (without limitation) printers, photocopies, facsimile machines, plotters, and combinations thereof (i.e., imaging apparatus commonly known as “all-in-one” imaging apparatus or “multifunction peripherals”). Example of imaging processes that can be used by imaging apparatus include electrophotographic imaging, including laser printing, and ink printing, including ink jet printing. Two primary types of imaging media are provided to imaging apparatus via a cartridge. These primary types of imaging media include wet ink and dry toner. Dry toner (“toner”) is commonly provided as powdered carbon black or very small particles of plastic (as in the case of non-black toners).
When the imaging media within a cartridge becomes depleted, the user typically replaces the spent cartridge with a replacement cartridge that contains additional imaging media. The user may not always have a replacement cartridge on hand, or the replacement cartridge may not be easily accessible. Accordingly, a user may be put in the position of not being able to complete an imaging job due to a lack of imaging media.
Some imaging apparatus are provided with imaging media quantity detectors which allow a user to have advance notice of a low imaging media condition, and thus take appropriate steps to secure a replacement cartridge. For example, the imaging media quantity detector can be a level detector to detect a level of toner or ink in an imaging cartridge. However, such quantity detectors are not found in all imaging apparatus, and typically are not included in relatively inexpensive imaging apparatus. Further, such imaging media quantity detectors are not always accurate. Another prior art method for detecting impending depletion of imaging media in a cartridge is using a so-called “pixel counter”. The pixel counter essentially comprises an algorithm which is executed by a processor in the imaging apparatus and which calculates (estimates) the usage of imaging media based on the number of pixels imaged by the imaging apparatus since the time the current imaging media cartridge was installed. However, such pixel counters are not always accurate, with obvious undesirable consequences (specifically, the imaging media in the cartridge becomes exhausted before the pixel counter indicates it should be exhausted).
With respect to certain dry toner cartridges, a user may notice fading of the image on imaged sheets of media, indicating a pending toner depletion condition. In the absence of an accurate imaging media quantity detector, this fading will most likely be the first indication that the user receives indicating a pending toner exhaustion condition. In certain instances the user may be able to extend the life of the toner cartridge by rocking it back-and-forth a number of times to redistribute the remaining toner within the cartridge. This may allow approximately 30 to 40 additional pages to be imaged using the toner cartridge before the cartridge is depleted of toner. In some cases this will provide the user with sufficient additional imaging capacity to allow the user time obtain a replacement cartridge, and more specifically, to allow the user to complete the current imaging job before replacing the cartridge. However, toner cartridges are now more commonly designed as “no-shake” cartridges, which incorporate baffles and/or an agitator within the toner cartridge to more evenly distribute toner within the cartridge, and thus reduce the fading which is manifested before depletion of the toner in earlier cartridge designs. Such “no-shake” cartridges only provide a user with approximately 5 to 10 pages of remaining imaging capacity after the first signs of toner depletion appear. In this case it will frequently occur that a user will not be able to complete a printing job without replacing the cartridge. If a replacement cartridge is not readily at-hand, then the user will need to interrupt the imaging job and continue it later once a replacement cartridge has been installed in the imaging apparatus.
When the imaging media cartridge contains liquid ink, and in the absence of an accurate imaging media quantity detector, the first indication the user may receive that the cartridge is in need of replacement is when the ink is exhausted from the cartridge. Thus, unlike the situation with toner cartridges, with ink cartridges the user must interrupt an imaging job upon the first indication of cartridge depletion, unless a replacement cartridge is readily at-hand.
What is needed then is a way to reduce the effects which result from depletion of prior art imaging media cartridges.